Vendor guidelines - Accuton:

Accuton produces a unique line of ceramic inverted dome drivers. Far from being fragile, the super rigid ceramic domes were recommended to me as producing a uniquely transparent sound. Aside from the ceramic dome material, these are otherwise conventional (albeit excellently designed & crafted) inverted dome drivers. Note especially their published distortion graphs! The most recommended are:

1. D²20/6, a 3/4" (20 mm) super tweeter. With claimed frequency response out to 100  and a diamond (sic!) inverted dome diaphragm, this is easily the most expensive and arguably the best conventional electrodynamic tweeter ever made. The few LDSG respondents whi've been fortunate enough to hear it report that it is indeed an exceptional unit. Whether it's worth its $2800/ea price tag is another matter.  view   response/distortion 


2. C²12/6, a 1" super tweeter. Featuring usable response out to 30 kHz, this unit still has a remarkably low 700 Hz Fs and exceptionally flat response down to 2 kHz. Cone breakup occurs well over 20 kHz. With its 100 W filtered power rating, this is one of the few super tweeters which can be used in a 2-way system.  view   response   distortion   step response   waterfall 


3. C²23/6, a 1.2" tweeter. Featuring response similar to the C2-12 in the audible range (a little lower on the bottom end and a high end that still extends past 20 kHz), the C2-23 adds the virtues of even greater power handling and an incredibly low (for a tweeter) Fs of 350 Hz! This is an expensive unit, but like the Jordan JX53 and Human 002, Xmax is high enough to make it suitable for use in 2-way designs.  view   response   distortion   step response 

   Note:	The C223/6, along with the Hiquphon OW I/II/III, Human 002, Scan-Speak R2904/7000, Morel MDM33, and the Alison Acoustics 4010203 (available only as a replacement part for Allison loudspeakers) are considered by many to be the ultimate electrodynamic tweeters.

4. C²44/8, a 2" midrange. Rated for 1 kHz to 12 kHz operation, this unit is ruler-flat, on- and off-axis, from 500 Hz (Fs is 390 Hz) out to 5 kHz. It's still flat out past 10 kHz, but off-axis response drops once you get past 5 kHz. Certainly in the running for the best midrange on the planet!  view   response   distortion   step response   waterfall 


5. C²89/T6, a 3.5" mid/bass featuring a titanium VC former. The idea of a 3.5" mid/bass driver stretches credibility a bit, but this unit pulls it off as well as the fundamental laws of physics will allow. With an Fs of 34 Hz, and recommended for use from 40 Hz to 4 kHz, the passband isn't as flat at the previously discussed Accuton drivers. There's a 1-2 kHz plateau in the published FR, but it's not clear wither this is real or a measurement artifact representing the baffle step of the test setup. Also available in an 13 Ohm model for parallel driver applications.  view   response   distortion   step response   waterfall 


6. C²95/T6, a 5" mid/bass featuring a titanium VC former. Perhaps, the most articulate 5" on the market, this diver is easily used out ot 2 kHz, with adequate cone control out to 3 kHz. Also available in an 11 Ohm model for parallel driver applications.  front view   back view   response   distortion   step response   impedance   waterfall 


7. C²220/T6, an 8" woofer featuring a titanium VC former. With its inverted dome ceramic diaphragm, this is one of the most distinctive drivers on the market, and certainly among the most articulate 8" drivers in current production. The response above 1 kHz and cone breakup above 3 kHz stronly recommend against using this as anything but a woofer. Also available in an 11 Ohm model for parallel driver applications.  front view   back view   response   distortion   step response   impedance   waterfall